1. Field of the Invention
The present invention relates to an injection molding machine having a drive source which is of a linear motion type electric motor.
2. Description of the Related Art
An injection molding machine includes various mechanisms such as an injection mechanism for axially moving a screw to perform injection operation, a clamping mechanism for opening, closing and clamping molds, an ejector mechanism for axially moving an ejector pin to extrude a molded product, and a nozzle touch mechanism for touching a nozzle to the mold. Each of these mechanisms has its axis (hereinafter referred to as linear motion member) arranged to be linearly driven. A screw is an example of such a linear motion member.
In a hydraulically operated injection molding machine, it is easy to cause linear motion of these linear motion members, by driving the members with a hydraulic cylinder. On the other hand, in a conventional electrically operated injection molding machine, a rotational output of an electric motor is converted into a driving force (hereinafter referred to as linear driving force) which acts on the associated linear motion member in the direction along which the same member moves. This is done with a conversion mechanism, such as a ball screw and nut, so that the linear motion member is moved by the linear driving force.
In this manner, a conventional injection molding machine requires a conversion mechanism, and is hence complicated in construction and high in cost. Moreover, it requires space for installation of the conversion mechanism, and has the drawback that the whole arrangement becomes large in size.